1. Field of the Invention
This invention relates generally to cable lubricants and lubricating methods.
2. Brief Description of the Background Art
It is often necessary to pull a metal cable or wire, or a cable protected by a plastic sheathing through a plastic or metallic or other smooth surfaced duct, tube, or housing. Despite the fact that the cable and the housing through which the cable is to be pulled both have relatively smooth contacting surfaces and thus relatively low coefficients of sliding friction, it is often necessary to provide a cable lubricant to facilitate the pulling of the wire or cable, especially when the housing conforms tightly to the cable or where long lengths of cable are involved. For ease of application it is preferable that the lubricant be in a liquid or colloidal, i.e. gell state. However, the nature of the lubricated surfaces, particularly their smoothness, often results in very low adhesion between the lubricant and the lubricated surface resulting in ineffective lubrication. Moreover, since it is often necessary that the wire or cable pulling operations be conducted over extended periods of time and under various temperature conditions it is preferable that the cable lubricant has good stability both over time and over a wide range of environmental conditions.
In the past, a variety of lubricants have been utilized for facilitating cable pulling and wire drawing including thixotropic paraffin-based gells, and polyethylene oxide gell-like semi-liquid coatings. Polyethylene oxide lubricants for cables are disclosed in U.S. Pat. Nos. 3,925,216 and 4,111,820. The lubricants disclosed in these two patents are water soluble and applied in a liquid state. However, U.S. Pat. No. 3,925,216 possesses inferior friction reducing properties as compared to a thixotropic gell and rapidly evaporates so that little lubricant, if any, remains on the cable or wire after a pulling operation is completed. U.S. Pat. No. 4,111,820 overcomes the disadvantages of the prior art by using a dispersing agent to increase the viscoelasticity and lubricity of the solution. While these synthetic polymeric lubricants have considerable lubricating properties, they suffer from the disadvantage that they have low adherence to the surfaces being lubricated.